Packaging finely divided materials



Nov. 15, 1960 2,959,900

' E. S. WOLLETT PACKAGING FINELY DIVIDED MATERIALS Filed Oct. l2, 1956 2 Sheets-Sheet 1 aaa---V-'L l INVENTOR P/(5575 Wam;

ATTORNEY Nov. 15, 1960 E. s. woLLE'r'r 2,959,900

PACKAGING FINELY DVIDED MATERIALS Filed Oct. 12, 1956 2 Sheets-Sheet 2` zal 1 NVEN TOR kA/557.5. W644E77;

ATTORNEY United States Patent O PACKAGING FINELY DIVIDED MATERIALS Ernest S. Wollett, 6949 Greenvale St. NW., Washington, D.C., assignor of two-thirds to S. G. Leoilier Filed Oct. 12, 1956, Ser. No. 615,651

13 Claims. (Cl. 5ft- 24)Y This invention relates to the packaging of finely divided materials that must be readily reducible again to the iinely divided condition, and aims generally to improve the same. More particularly, the invention relates to the packaging of such materials in the form of compacted rectangular blocks of substantial size, and more especially to the compacting of clay powder into rectangular blocks of, say, f-ty pound size, in a mum of space commensurate with the ability of the clay to freely return to its powdered form for use as fillers in rubber manufacture, or for use of the ceramics industry, or the like.

Clay, flour, and like finely divided goods, have heretofore been shipped principally in bags, or boxes. Such goods contain large quantities of air, and do not readily settle into a compact form, even when subjected to vibration or shaking. Hence the boxes or bags have had to be correspondingly large because of the inherent bulk of the product, and of relatively heavy stock to resist puncture and loss `of the powdered material. When an effort is made to mechanically compress such materials, the entrapped air is also compressed, and on release of the mechanical pressure, expands and ruptures the block. Attempts to pack such 4materials under vacuum have also not been successful because of fthe difficulty of screening against loss of the material, clogging of screens, and inability to scavenge the entrapped air from deep bodies of the material.

The present invention aims to overcome disadvantages attendant on prior methods of packing such materials, and to provide a new method and apparatus for producing a compacted but readily decompacted block from such materials, preferably rectangular, and preferably closely wrapped with paper or other wrapping material that is supported by `the denseness of the compacted material, thus minimizingpuncturing of the wrapper in handling and allowing lighter packaging to be used, and that in turn holds in place any sections of Vthe block that may be cracked olf by rough handling, thus to maintain the weight and shape of the packed goods.

With these general aims in mind, the invention has for particular objects, severally and interdependently, the provision of a novel method of compacting clay and like finely divided materials into form retaining but readily disintegratable blocks; the provision of new apparatus constructed to facilitate the practice of the novel method; the provision of a method and apparatus that enables the compacted block to be formed and handled during wrapping on the wrapper material acting like a pallet; and the provision of a new wrapped product adapted to be stacked and handled in a minimum of shipping and storage space for the Weight of the product commensurate with its being returnable to its finely divided form.

The invention also aims to provide new and useful subsidiary steps and features and subcombinations thereof contributing to the realization of the general objects of the invention.

The invention itself resides in the new methods and means for forming the blocks of finely divided material, in the successfully compacted blocks thereof, and in subordinate steps and elements thereof, as hereinafter eX- emplilied, and is more particularly pointed out in the appended claims.

In the accompanying drawings illustrating various features of the invention:

Fig. 1 is a more or less diagrammatic elevation partly in section, of an apparatus for packaging clay in accordance with and by the method of Ithe invention.

Fig. 2 is a similar View of apparatus that may be associated with the apparatus ofFig. 1.

Fig. 3 is a diagrammatic view of a conventional hydraulic system employable with the apparatus of Fig. l.

Fig. 4 is a perspective view of Va sealed packaged block of dry finely divided material according to the invention. Y v

Fig. 5 is a schematic diagram of means for automatically controlling the operation of the machine for the canrying out of the method.

Finely divided clay in bulk is so highly aerated and fluffy that a weight of fifty pounds of it occupies a volume of about 2974 cubic inches, i.e. a depth of about l4 inches in a l2 inch by 18 inch rectangular container (216 square inch cross section). Shaking can only reduce the volume slightly,` and when an attempt is made to mechanically compress the height of the body in a sealed container, the air entrapped in the clay is compressed, and re-expands when the pressure is removed, causing disintegration of the body. When attempts are made to yexhaust air as the loose clay body is mechanically compressed, much nely divided material is lost, screens are clogged, andv since the clay compacts quite densely against the compacting piston, but is more and more highly aerated as the distance fromthe piston and consequently the depth of clay through which air must escape) increases, only a limited amount of the air content can be withdrawn, with the result that attempts to form blocks of clay, and like finelyY divided aerated materials, by the application of mechanical pressure and vacuum, per se, have been unable to yieldsatisfactory form retaining blocks.

The present invention, however, provides a new method of compacting such finely divided clay, herein ltaken as representative of clay and finely divided materials in general, by initially only'partially compacting the clay mechanically in a sealed mold; then breaking down or subdividing the compacted layer of clay just ahead of the compacting piston and providing air escape channels therein while maintaining the clay under pressure; then venting the air pressure .through the channels so provided; and then evacuating residual air through such channels while compacting the clay from its initial partly compacted condition to its final condi-tion as a self Sustaining block, the initial compacting and channelling avoiding undue carry-out of finely divided clay during these latter steps.

In a typical example of the compacting of Tennessee kaolin into fifty pound blocks of 12 inch by 18 inch cross section by the present invention, when the finely divided substantially dry clay is dumped into the mold cavity, it is usually sloped at anV angle of repose, but in a Huid state. The piston being entered into the rnold cavity and having its lateral sealsexpanded against the cavity walls (as hereinafter described), the first advance of the piston tends to evenly or flatly distribute the flowable clay in the mold cavity and solidify vit enough so that its flowability is reduced. l This initial partial compacting of the clay may reduce the depth of the bulk` clay body from about 14 inches to about 9 inches. Since the mold is kept sealed during this initial compacting loss of clay from the mold is prevented and the pressure of the air within it is raised from about l atmosphere to about 2 to 3 atmospheres. As the clay packs just ahead of the piston, the air expressed `from it moves toward the bottom of the mold, increasing the pressure of the air thereat without compacting very much the clay remote from the piston.

If now an attempt is made to vent or exhaust the air from the partially compacted block in this condition, rst, the time required for passage of the compressed air from the lower parts of the mold through the partially compacted area of clay ahead of the piston is excessive; second, the tight packing of the clay across any vent port or screened vent port, clogs the same; third, if the piston is raised to relieve the pressure, the expansion of` the entrapped air reverses the partialcompacting of the clay; and fourth the expansion of such air carries excessive quantities of finely divided clay through the vent or exhaust openings.

But by admitting more compressed air to the mold, the present invention, peculiarly, largely eliminates these diiculties. Preferably this added compressed air is admitted through a screened opening in the center of the piston and about 2 inches in diameter and impinges initially on the central ,portion of the layer of clay compacted against the piston. In so doing the impinging air ruptures the compacted layer of clay and forms a sort of crater at the center of the clay and generally radial channels or fissures through it and through the underlying highly aerated clay, some of which fissures extend clear to the margins of the mold, and which subdivide the body of clay into smaller bodies with air collecting spaces or venting channels relatively free of clay between them. In the typical example, with about 2 to 3 atmospheres pressure in the mold (say 29 pounds per square inch, gauge), the added air may be suddenly admitted at a pressure of about 4 to 5 atmospheres, say 60 pounds per square inchgauge. The air admission also tends to drive the clay rather rmly against the sides and into the corners of the mold.

When the rush of added air into the mold dies out, after a fraction of a second, the mold is vented to atmosphere, preferably through the central screened piston opening through which the compressed air was admitted. This mode of venting is deemed particularly desirable, as the rapid ow of highly compressed air from the clay through the relatively clay-free fissures or channels therein carries most of the air-borne lines from the clay body toward the crater formed by the impinging compressed air, where they are retained by the screen. Because the fissures and` crater are relatively free of clay, the airborne clay carried to the screen is not sutiicient to clog it, and is of course displaced from the filter by the next air jetting operation.

When the pressure in the clay has been reduced substantially to atmospheric pressure in this way, which may require a half `second or so, the marginal seal of the piston against the walls of the mold is opened, and a vacuum reservoir, containing a vacuum measured at to 25 inches of mercury in the typical example, is connected to the space above the thus opened margins of the piston. The application of this vacuum causes further air to be evacuated from theA body of the clay through the channels previously mentioned in a generally outward radial direction to the margins of the mold. Since the pressure difference is less than that occurring in the initial venting operation; since the clay is Well compacted near the outer walls of the mold; since the venting has already carried most of the air-borne lines to the central part of the body; and since the opening about the piston may be quite large (equivalent to an opening nearly an inch in diameter, when the 12" X 18 piston has a clearance of only .005 from the sides of the mold), very little air-borne clay is carried past the piston during the initial evacuation.

When the vacuum has built up enough in the mold (substantially full vacuum can be reached in a fraction of a second) the piston is again advanced, while maintaining the vacuum, to decrease the height of the mold cavity, in the typical example, from about 9" to about 5% inches, thus to compress the clay, that originally occupied about 2974 cubic inches, into a block having a volume of only about 1115 cubic inches or about of its original volume. This degree of compacting is attainecl` with a pressure of about 200 lbs. per square inch on the clay, and even if such pressure is raised by 50% or more, say to 320 lbs. per square inch, substantially no further reduction in the height of the block can be obtained.

In the preferred practice of the method, the compacted block is formed on a sheet of paper, or on the leading portion from a roll of paper, which is placed between the mold bottom and mold walls, and sealed to the latter during the molding operation, and which is employed to move the block and for wrapping the same.

In the typical example, when the upper piston has advanced to the final compacting position, the pressure supporting the mold bottom is reduced to a point at which it is just sut`n`cient to hold the mold bottom (and paper when present) up against the block. The piston is then further advanced, as the mold bottom is lowered and gently pushes the block and the mold bottom ahead of it until the block is completely out of the mold cavity. Then further lowering force is applied to lower the mold bottom and block until the top of the block is about 2% inches below the lower edge of the mold box, at which point the leading ends of the lateral edges of the paper, if present, are disposed on top of a movable carrier, to which the paper may be gripped in any suitable manner so that it and the block may be pulled from the molding press to a wrapping zone at which the sheet of paper, cut to the proper length, may be wrapped snugly about the block and sealed, either manually or mechanically.

As above noted, the combination of steps by which the clay is compacted, `and especially the jetting of the fissuring air into the top central portion of the block, tends to partly concentrate the clay against the side walls of the box, so that if during the mechanical pressing, any soft spot does remain, it will generally occur at the top center of the block where it will not cause crumbling of the side Walls and corners of the block during wrapping. When the block is snugly wrapped, the high density of the clay supports the wrapper against puncturing, and even if a part of the block cracks off within the wrapper, the wrapper holds it in place, maintaining the shape and true weight of the package.

Further, when the clay is to be employed as a filler in the manufacture of rubber or plastic goods, the wrapper may be formed of a plastomer film or sheet that is compatible with and soluble in the material to be iilled, and the entire package may be added as a measured quantity in the mill or mixer. Similarly when Hour or thc like is being packaged, the wrapper can be either of paper, and be removed, or of a soluble gelatin film or the like, that may be incorporated in the bread or cake mix without deleterious effect on the product to be prepared.

A preferred apparatus for practicing the new method, as illustrated in Fig. l, comprises a frame 10 proportioned to sustain the weights of the parts and the hydraulic pressures employed for mechanically compacting the clay. Such frame, in the form shown comprises a base plate 10a vertical tension supporting columns 10b, at the corners thereof, supporting sleeves 10c surrounding the lower portions of such columns, a mold box supporting frame 10d positioned by the columns 1Gb and supported by the sleeves 10c and a piston supporting platform 10f carried by the upper ends of columns 10b.

The mold box 11, which for purposes of illustration, may be considered as rectangular and of a cross section of l2 x 18" with a height of 14 or more, in the form shown comprises a positioning flange 11a that rests on top of the marginal supporting frame 16d, and which may be notched at its corners to lit around the column b, as shown. The lower edge of the mold box, in the form shown, lies substantially ilush with, or slightly below, the under surface of the mold supporting frame 10d, and is provided with a sealing gasket 111c of rubber or other suitable material.

The mold bottom, in the form shown, comprises a platform 12, movable vertically by controllable means such as a conventional hydraulic system of suitable capacity, comprising the hydraulic piston 12a that travels in a hydraulic cylinder 12b, packed at 12C about shaft 12d and provided with elevating and lowering chambers 12f and 12g, to and from which fluid under pressure, preferably hydraulic fluid, may be supplied from a suitable pressure pump and exhausted to a suitable reservoir, as by a dual 3way control valve 12h that may be operated manually, or by remote control, or by suitable timing or limit control apparatus, as will be understood by those skilled in the art. For the purposes of the present invention, the system is further provided with a by-pass comprising a stop valve 12k and a constant pressure maintaining relief valve 12m, that is adjusted to just balance the weight of the piston and platform 12., 12a, 12d with the weight of the compressed block thereon, so that a very slight pressure on the top of this block will produce downward iioating of the system.

The mold bottom, in the form shown, contacts the sealing ring 11b of the mold box (with the paper sheet, hereinafter described, intervening) and may Contact the mold supporting rim 10d at the upper limit of its stroke. When lowered, the upper surface of the mold bottom 12 aligns with a take-away platform 13 (about 8" below the bottom of the mold box 11 where a block about 5% high is to be formed). At either side of the platform 13, in the form shown, travelling carriers 14 are provided, that are adapted to be moved longitudinally away from the machine by any suitable means, that may be controlled manually, by limit switches correlated with the lowered and raised positions of the mold bottom 12, or otherwise. Suitable grippers 15, illustrated as jaws drawn downwardly and inwardly toward the carriers 14 by solenoids 16 against the action of springs (not shown), are provided for gripping the margins of the paper sheet 17 to the carriers 14 when the mold bottom 12, sheet and block are in lowered position, for drawing the block from the mold bottom 12 onto the take away platform 13, using the paper sheet 17 as a pallet for this purpose. The paper sheet 17 may be drawn from a continuous roll 17a, mounted in any suitable position, and is of a width (say 24" for a block 18" wide and 5 1A thick) that will enable it to be folded over the ends of the block after being wrapped around it, with enough overlap for sealing, as with a strip of heat-sealing resin impregnated paper tape, for example. Such strips of tape may be applied manually, or in the wrapping machine (which per se forms no part of the present invention) or may be applied to the under sides of the leading edge and the marginal edges of the sheet while it is gripped between the mold bottom 12 and mold box 11, if desired. When the paper 17 is drawn from a roll 17a, as shown, means is provided for cutting a proper length of sheet from the roll, as exemplied by the shear blade 18 in Fig. l, which may be operated manually, or by a limit switch, when the carriers 14 have drawn out the sheet the required distance, say 35 or 36 inches where the block is `to be l2 inches long by 5% inches thick by 18 inches wide, with respect to the direction of travel of the carriers 14.

As above mentioned, when the paper sheet :17 is used, as is preferred, it passes between the mold bottom 12 and the lower end of the mold box 11, is pressed against the gasket 11b by the mold bottom, in the position indicated by the dotted line 17 in Fig. 1, and is lowered with the mold bottom 12 to lay its leading edge on the platform 13 and carriers 14 between the grippers 15 that Y 6 are then operated to grip the paper to the carriers 14 for movement therewith.

The means provided for loading a measured quantity of clay or the like into the mold box 11 may be of any suitable form, and is herein exemplified by a hopper 20 for receiving the dry, powdered clay, provided with a suitable feeder or agitator 21, and with a cut-off shutter 22, herein shown as integral with the weighing box 23 that rests on the platform 24 of a scales 2S the beam of which rises when the measured quantity of clay is added to the tare-weight of the parts. The weighing box 23 and shutter 22 are moved froml the scale platform 24 across a feed platform 26 until the box 23 aligns with the mold box 11 to dump its contents therein. Such motion may be effected manually, but is preferably effected by a hydraulic ram 27, of conventional construction, the valves of which are actuated inter alia, by a trip switch controlled by the scalebeam for advancing the ram, and by a limit switch actuated when the box 23 reaches its idle position on the platform 26, which limit switch is bypassed when the clay is to be dumped, causing the ram 27 to move the box 23 to its full dump position. After dumping the cycle of the loading mechanism retracts the box 23 to its filling position, and the scale beam operated limit switch advances it to its idle position when it has been refilled. Alternatively, the beam controlled switch may stop the hopper feed means 21, and the ram may be controlled by trip switches correlated with the end of the compacting cycle of the machine or with the rising operation of the mold bottom 12 to move the weighing box to its dumping position directly from the lling position. And when the average density of the aerated material is suiciently constant, the box 23 may simply accommodate a predetermined volume of the material, the scales may be dispensed with, and the box 23 may be retained in the position shown, or moved to the plat- -form 26, as desired, after it is filled.

The compacting piston 30, in the form shown, is carried by the piston rod 30a of a hydraulic device 3012, per se of conventional form, that comprises lowering and lifting pressure chambers 30C and 30d with travelling piston 30j and fluid inlet and relief lines 30g, 30h controlled by dual 3-way pressure inlet and relief valve means 30k that may lbe operated manually or automatically, as by solenoid means actuated by trip switches associated with the retraction of the weighing box 23 from the compacting machine, by timing means, or otherwise. As is conventional, the hydraulic inlet and outlet lines A and B of the Valves 12h and 30k are preferably connected directly to the constant-pressure output and return lines A and B', respectively, of the pressure system `(Fig. 3)

that may comprise reservoir R, pump 12R and constantA pressure by-pass 121, as shown.

The piston rod 30a has packed passage through both heads of the cylinder 30d, 30C and is traversed internally by two pneumatic fluid conduits 31 and 32. The conduit 31 communicates with a pneumatically expansible gasket 33, adapted when inated to project from a peripheral groove in the piston 30 into sealing engagement with the walls of the mold box 11, and when deflated to afford clearance between piston 30 and said walls, that may be of the order of .005 inch where clay is being packed in 50 lbs., 12x18 x 51/4 blocks.

The conduit 32 communicates with a central recess 34 in the center of the piston head, that is covered with a screen or filter cloth 35, about 2 in diameter in the case just mentioned.

A mold cap or head 36 is slidably mounted on the piston rod 30a (the joint being packed as shown) and is provided at its lower end with a sealing gasket 36a for sealingly engaging the upper end of the mold box 11. Suitable means, illustrated as sliding guide ears 36h are provided for guiding the mold cap and piston into accurateY alignment with the mold box 11. The interior of the mold cap 36l communicates through a flexible conduit 36C with a vacuum and relief valve of suitable construction.

The pneumatic pressure and relief valves associated with lines 31 and 32 (not shown) may be of any suitable construction, say 3way valves. The vacuum and relief valve and systems associated with the conduit 36e may also be of any suitable construction, and may embody suitable means for separating the airborne clay from the evacuated air before it reaches the vacuum reservoir. For example, as indicated in Fig. 2, the vacuum 4conduit 36cmay pass to a central dust separating tube 37 that communicates at its top through a cloth lter 37a with a vacuum line 38 having a vacuum valve 39 operated by a solenoid G1, that may be associated with the hydraulic system for timing, and thence communicating with the vacuum reservoir in which a vacuum of from 10 to 29 inches of mercury (preferably about 25 inches of mercury) is maintained.

The lower end of the dust separating tube 37 may be closed by a flap valve 37b pivoted at 37e and suitably operated, as by a solenoid G2 that may be similarly associated. The outer housing 371c may communicate at its bottom with a fan l1 or other removal device for transferring the clay dust to a suitable collector or receiver.

As will be evident from the description of the novel method, the sequencing of the several operations of Vthe machine to carry the method into effect may be controlled manually, or by timer means, or each step of the operation may be controlled in response to completion of the prerequisite step, or the system may be controlled by any combination of such modes of operation. Merely for clarity, and without limiting the invention thereto, one mode of controlling the operation will now be set forth with reference to Figs. 1 and 5, by way of example:

At the outset, the wrapping sheet 17 will be positioned in the machine; the charging box 23 will be filled with the charge of finely divided pulverulent material; valves 12h, 30k and 27h may be at neutral or hold position with the piston 12a at the bottom of its stroke, piston 30j at the top of its stroke and piston 27a stopped at the center of its stroke.

Referring to box A, Fig. 5, the closing of starting contacts A1 may energize stick-solenoid A2 from power source P to move valve 12h, biased to hold position as by a spring means 12x, to position R for raising the mold bottom 12, which, on approaching the top of its stroke, for an interval closes contacts A3 that energize the loader advancing stick-solenoid B1 (box B) initiating the loading cycle.

The solenoid B1 (box B) moves valve 27b from hold H to advance A moving charging box 23 from its idle position on 26 (Fig. l) to dumping position, allowing contacts B2 to close in the stick-circuit of solenoid B1 before contacts A3 are released. At dumping position a part moving with box 23 opens contacts B3 deenergizing solenoid B1 and returning valve 27h to neutral position; and simultaneously contacts B4 are closed, energizing stick-solenoid BS that moves valve 2,7b to retract position R to draw box 23 to its filling position.

As soon as box 23 is drawn back onto platform 26 a part moving with box 23 momentarily closes contacts B6 to initiate operation of piston 30 as hereinafter de,- scribed in connection with box C. As box 23 reaches its filling position it opens contacts'B7 in the stick circuit of relay B allowing valve 2 7b to return to hold position H. When the weight of clay delivered to the box 23 operates scales 24 these scales close restart contacts B8 in the pilot circuit of advance solenoid B1, and the box 23 is moved back onto platform 26 at which point a part associated with box 23 opens contacts B2 in the stick-circuit of solenoid B1, terminating the loading and filling cycle.

When the retraction of box 23 closes contacts B6, stick-solenoid C1` is` energized moving valve` 30k from its hold" position yHl to position L to lower piston 30.

A part moving with piston 30 closes contacts C2 as soon as the piston 30 enters the mold box 11, to energize stick solenoid D1 to move valve 31a from its vent position V to its sealing position S and inate seal 33 through conduit 31.

Following the inflation of seal 33, piston 30 continues to lower until it has compressed the aerated clay to a depth of say, 9 inches, at which point contacts C3 are opened to break the stick-circuit C1 and allow valve 30k to return to its position H to stop piston 30 at that point. Simultaneously, contacts C4 are closed to initiate the air-jetting and venting cycle that will now be described.

The closing of contacts C4 euergizes stick-solenoid El, that moves valve 32a from its closed position C to its jet position I, admitting jetting air through line 32 (Fig. l) to channel the initially compacted clay. Differential pressure operated device 32h, when the static pressure in conduit 32 becomes equal to that entering valve 32a, operates to open contacts E2 and close contacts E3 to deenergize solenoid E1 and energize solenoid E4, thus moving valve 32a to vent position V.

The differential pressure operated device 32e (box F) having been retracted when the pressure in conduit 32 became greater than atmospheric, again advances when that pressure becomes substantially equal to atmospheric, and a part moved thereby then momentarily opens contacts F1 in the stick-circuit of solenoid D1, to release that solenoid and return valve 31a to its vent position V, thus deating the seal 33.

At the same time device 32e momentarily opens contacts F2, in the stick-circuit of solenoid E4, thus releasing that solenoid and returning valve 32a to its closed position to ready the mold for the application of vacuum to its interior.

Following the deflation of the seal 33 and closing of the jet-and-vent conduit 32, the device 32e` (box F) closes contacts F3 for initiating evacuation of the `mold by energizing stick solenoid G1 and parallel solenoid G2 (box G) to open vacuum valve 39 and close vent valve 37b, also shown in Fig. 2.

The differential pressure device 36g operates when the vacuum in conduit 36C becomes substantially equal to that entering valve 39, and closes contacts G3 to re-energize stick-solenoid C1 and re-start downward motion of the piston 30 for the second stage of compacting. When the second compacting is completed, a part moving with piston 30 opens contacts C5, which are in the stick circuit of solenoid G1, thus closing the vacuum valve 39 and opening the vacuum venting valve 37b. Contacts CSa in this stick circuit of solenoid C1 may be opened simultaneously with contacts C5, to stop the descent of piston 30 at this point if desired, or such cir cuit breaking contacts may be omitted, in which case contacts G7 (hereinafter described) may also be omitted.

The differential pressure device 36h (box G and Fig. 2) having been retracted when the pressure in conduit 36e became substantially less than atmospheric, operates as such pressure returns to approximately atmospheric, mo mentarily opens contacts G4 in the stick circuit of solenoid A2, thereby returning valve 12h to its hold position H, momentarily closes contacts GS to energize sticksolenoid G6, to open the by-pass stop valve 12k and thus unlock the mold bottom 12 so that it can be lowered by pressure on its top surface, and momentarily closes contacts G7 to re-energize solenoid C1 and restart lowering of piston 30.

When piston 30 has pushed the block clear of the bottom of the mold box 1l, parts moving with it close contacts C6, energizing mold bottom lowering stick-solenoid A4, and momentarily open contacts C7 in the stickcircuit of solenoid G6.to close the bypass stop valve 12k, thus initiating positive lowering of the mold bottom 12 to move the` block well clear of the mold box 11, and

9 also momentarily closecontacts Clipand open contacts C9'forenergizing stick-solenoid C10 and'de-energizing solenoid C1 to initiate upwardmotion of piston 30, that proceeds until piston 30 reaches its upper limit, when a part -moving with it opens contacts C11 inthe'stickcircuit of solenoid C10, de-energizing it andreturning valve Silk to its hold position H.

When the mold bottom 12, started downwardly by closing of contacts C6, reaches alignment with the platform 13, a part moving with it openscontacts A in the stick circuit of solenoid A4, allowing valve 12h to return to its hold position H to terminate the` lowering, and closes contacts A6 to energize stick-solenoid I1 and parallel solenoid means J2 (also shown in Fig. l). Solenoid J1 moves a valve J3, similarto'valve 12h, from its hold position H to its drive position D, and solenoid means J2 actuates grippers 15` (Fig. l) to grip the edges of the sheet 17 to the carrier means 14. The moving of valve J3 to position D initiates drive of the carrier means 14 to draw the sheet 17 and the block carried by it outwardly across the platform 13 toward the wrapping zone. When suchmotion has drawn the block clear of the compacting machine, and far enough in the preferred embodiment to draw past cutter 18 a sutilcient length of paper 17 with which to wrap the block (36 inches in the case assumed for illustration), a part moving with the carriers 14 opens contacts J5 in the stick circuit of solenoids J1 and I2 and closes contacts I4 and J6. The closing of J4 energizes cutter operating stick solenoid K1 to operate the cutter v18 to sever the sheet 17; the opening of J5 de-energizes stick solenoids J1 and J2, terminating the driving motion of carriers 14 and releasing grippers 15; and the closing of contacts J6 energizes stick solenoid J7, moving valve J3 to its reverse position R andinitiating return of the carriers 14 to their initial position (Fig. l) at which a part moving therewith opens contacts I8 in the stick circuit of solenoid J7 to allow the valve J3 to return to its hold position H to stop the motion of the carriers 14.

On operation of the cutter 18 by stick-solenoid K1 con tacts K2 in the stick circuit of solenoid K1 are opened, and contacts K3 :and K4 are momentarily closed. K2 as shown, releases the cutter operating solenoid and allows the cutter to return to its open position to which it may be biased, as by a spring K5. Contacts K3 may initiate operation of the wrapping machine, and contacts K4 may apply power to the pilot circuit of stick solenoid A2 in parallel with the starter button A1, to automatically restart the loading and block forming cycle now fully described.

The wrapping of the block, as above noted, may be effected either manually, or by automatic machine. In either case, .as shown in Fig. 4, the sheet 17 of paper, water-resistant paper, or lm compatible with intended use, is preferably folded about the block with its foreand-aft edges overlapped as shown, and with a sealing strip 17a applied over the exposed portions at the outer superimposed edge, the ends being then folded as shown, with a sealing strip 17b applied on the lapped edges at each end as shown, although any other mode of covering the block may be employed within the broader aspects of the invention.

Where the mold box 11 and piston 30 have been referred to herein as rectangular in cross-section it is to be understood that the corners of the mold box and of the piston may be lilleted or'rounded on a suitable nadius, say 1A inch for a package 12 by 18 inches in cross-section, to facilitate tight sealing of the expansible seal 33 and avoid undue fragility at the edges and corners of the block.

While there have been described herein what .are at present considered preferred embodiments of the invention, it will be obvious to those skilled in the art that modifications and changes may be made therein without 10 departing from the essence of the, invention. It is therefore'rto be understood that the exemplary embodiments are illustrative and not restrictive of the invention, the scope of which is defined in the appended claims, and that all'modiflcations thatcome within the meaning and range of equivalency of the claims are intended to be included therein. f

I claim: f Y

1. A method of compacting nely divided dry powdered material that comprises (a) mechanically compressing an aerated body of the material and its air content to reduce its volume by about one-third, (b) injecting higher pressure air into the compressed :aerated body to Y produce venting channels therein, (c) venting the s0 channelled body to atmospheric pressure, (d) evacuating the so channelled aerated body through said channels, (e) further mechanically compressing the body while maintaining such evacuation to reduce its volume by approximately yanother, third, and (f) restoring the resulting compacted body to atmospheric pressure.

2. A method of packaging dry powdered materials that comprises compacting the material, by the method of claim l, on an underlying sheet of wrapping material sufficiently large to wrap the compacted body, employing the sheet of wrapping material asa pallet forl moving the compacted body to a wrapping zone, folding the sheet snugly about said compacted body at said wrapping zone, and sealing the package. v

3. A method of compacting nely divided powdered material, into a rectangular parellelepiped having a volume much reduced as compared to the volume of the uncompacted material, that comprises (a) placing the material in a rectangular mold having a movable top wall and sealing they mold, (b) advancing the movable top wall to compress the material and its air content to about twice the ultimate volume to be attained, (c) injecting higher pressure air into the center of the top of the so compressed body to subdivide it and produce venting channels therein, (d) venting the so channelled body from the center of the top of the body to atmospheric pressure, (e) evacuating the so channelled body peripherally of its top surface, (f) advancing the movable top wall to compact the material to said ultimate volume while maintaining said evacuation, (g) terminating the evacuation and restoring atmospheric pressure to the body, and (h) removing the compacted body from the mold.

4. In the mechanical compacting of aerated dry powdered material into blocks of reduced volume, the improvement that consists in partially compressing the aerated material, then producing vent channels in the partially compressed material while holding it in its partially compressed state, which vent channels radiate from Y the center of one face of the body of material toward its periphery, then venting and evacuating the material through said channels, the flow of air during such venting through said channels being inwardly from the periphery toward said center, and the ow of air during the evacuation of said body of material being directed outwardly toward said periphery, and completing the compression of the material While so evacuated.

5. The method of compressing pulverulent material into rectangular blocks of the order of 3A cubic foot per block, with the aid of a mold having stationary side walls, a removable bottom wall, and a loosely iitting top or piston wall having means for sealing it to the side walls, that comprises depositing a volume of the material in the mold between said movable walls, sealing each of said movable walls to the side walls of the mold, advancing the movable top Wall into the mold to partially compact the material and compress the air within it, directing higher pressure air into the top surface of the partially compressed material to crater and fissure the same thus to form vent channels therein, releasing air from the channels so formed to the atmosphere, releasing the seal between the top and side walls, applying applied betweensaidtop and, bottom walls, andmoving the top` and, bottom walls, downwardly together to dis.- placefthe block` from, within` the side walls.

8. A method accordingAK to claim7; further comprising the step `ofseparating thefblockl and bottom Wall from the top wall after theblockhas, cleared the .lower edges of the sidewalls, andy laterallyremoving the block from said bottom wall.

9. A method accordingtoclaimY 8, further comprising the step of placing a palletusheet` over andy projecting beyond the bottom wall before closing it to the side walls` and dumping the material into the mold, and laterally removing the block from the bottom wall on saidl sheet.` 10. The method of compacting finely. divided mate.- rial that comprisesl placing a` body of` the material in a mold, partially compacting thebody of material, applying a jet of high pressure air through the-top surface of the body of partially compacted `material to penetrate into said body and crater and` fissure said body,`exha ust ing air from said craterV to4 atmosphere, applying a vacuum peripherally of the-mold to exhaust air from-,the ssure divided body of material,l and mechanically compressing the material whiler maintaining the vacuum- 11. In the-,mechanical ,compactingof aerateddry powdered materials into blocks o f reduced volumetl1e im?.

provenient that consists inf partially compressing the aerated material, then producing vent channels in the partially aerated. material by blasting higher pressure air thereinto while holding it-` in, its partially compressed state, then venting1 and evacuating to less than atmospheric pressure the material. through said channels, and completing,the` compression. of` the material while so evacuated. f

12. An improvement according to claim 11, in which the blast of: high pressure air is directed as a jet against the-center of one, face'of the partially compressed body of materialto penetratethereinto, and produces venting channels therein which radiate from the center of said face to the perpheryofthe body.

13. An-improvernent according to claim 12, in which the owof air duringthe venting of the` material through said, channels isV directed inwardly from the periphery toward, saidv center, and in which the iow of air during the evacuating of the body, of material is directed outwardly toward said periphery.

References Citedjin the le of this patent UNITED STATES PATENTS 282,045 Bower.; -e July 31, 1883 773,876 Lorillard Nov. 1, 1904 1,388,453 Davidson Aug. 23, 1921 1,452,100 Wheildon Apr. 17, 1923 2,004,465` Dietrichs June 11, 1935 2,014,555 Chekian Sept. 17, 1935 2,073,615 Johnson et al Mar. 16, 1937 2,149,790 Roesch Mar. 7, 1939 2,292,295` Royal Aug. 4, 1942 2,301,939-` Fischer Nov. 17, 1942 2,348,197,- Ernst et` al. May 9, 1944` 2,415,462 Cherry etal.` Feb. 11, 1947 2,506,769 Bergsteid.F May 9, 1950 2,671,940; Billner u. Mar. 16, 1954 

